In orthopedic procedures it is common to use a surgical cement, such as an acrylic bone cement, to affix a prosthesis to the bone, for example to fix a hip joint implant to the interior surfaces of the femoral canal.
U.S. application Ser. No. 07/769 004 filed Sep. 30, 1991 and a co-pending divisional thereof, namely U.S. Ser. No. 08/132 031 filed Oct. 5, 1993 , both assigned to the assignee of the present invention, disclose an advantageous apparatus for mixing such cement and loading it by gravity into a cartridge. The mixing and loading are carried out under subatmospheric pressure to minimize air or other gas bubbles in the mixed cement. The cartridge, loaded with cement, is then transferred to a bone cement injection device (conveniently referred to as a gun). One such bone cement injection device has a pistol-shaped body for releasably supporting a forward extending cartridge containing bone cement and further having a ram actuable by a manually moveable trigger for pushing bone cement out the front of the cartridge through a suitable nozzle and into the femoral cavity. For example, such a gun is disclosed in U.S. application Ser. No. 07/769 003 assigned to the assignee of the present invention.
The mixing and loading apparatus shown in the aforementioned U.S. application Ser. No. 07/769 004 and the injection device shown in above referenced U.S. application Ser. No. 07/769 003 have been successfully marketed for more than a year prior to the filing date of the present application.
The present invention arises from a continuing effort on the part of the present assignee to improve surgical cement, particularly bone cement, mixing and injecting apparatus and particularly to improve cartridges useable with such apparatus.
Further objects and purposes of the present invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.